title: Functional specialization for auditory-spatial processing in the occipital cortex of congenitally blind humans.
abstract: The study of the congenitally blind (CB) represents a unique opportunity to explore experience-dependant plasticity in a sensory region deprived of its natural inputs since birth. Although several studies have shown occipital regions of CB to be involved in nonvisual processing, whether the functional organization of the visual cortex observed in sighted individuals (SI) is maintained in the rewired occipital regions of the blind has only been recently investigated. In the present functional MRI study, we compared the brain activity of CB and SI processing either the spatial or the pitch properties of sounds carrying information in both domains (i.e., the same sounds were used in both tasks), using an adaptive procedure specifically designed to adjust for performance level. In addition to showing a substantial recruitment of the occipital cortex for sound processing in CB, we also demonstrate that auditory-spatial processing mainly recruits the right cuneus and the right middle occipital gyrus, two regions of the dorsal occipital stream known to be involved in visuospatial/motion processing in SI. Moreover, functional connectivity analyses revealed that these reorganized occipital regions are part of an extensive brain network including regions known to underlie audiovisual spatial abilities (i.e., intraparietal sulcus, superior frontal gyrus). We conclude that some regions of the right dorsal occipital stream do not require visual experience to develop a specialization for the processing of spatial information and to be functionally integrated in a preexisting brain network dedicated to this ability.
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Université de Montréal, Montreal, QC, Canada H3C 3J7. olivier.collignon@umontreal.ca
authors.forename: Olivier
authors.initials: O
authors.lastname: Collignon
authors.forename: Gilles
authors.initials: G
authors.lastname: Vandewalle
authors.forename: Patrice
authors.initials: P
authors.lastname: Voss
authors.forename: Geneviève
authors.initials: G
authors.lastname: Albouy
authors.forename: Geneviève
authors.initials: G
authors.lastname: Charbonneau
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001766:Blindness / Q000151:congenital* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000503:physiopathology; D009473:Neuronal Plasticity / Q000502:physiology; D009778:Occipital Lobe / Q000503:physiopathology*; D013028:Space Perception / Q000502:physiology*; D019987:Persons with Visual Disabilities